1. Field of the Invention
The present invention relates to a liquid crystal display apparatus and a method of manufacturing a substrate of the liquid crystal display apparatus, and more particularly to a liquid crystal display apparatus with retardation layer formed in a liquid crystal display panel and a manufacturing a substrate of the liquid crystal display apparatus.
2. Description of the Related Art
A general retardation film is used for a liquid crystal display apparatus. The retardation film allows a linearly polarized light to pass through the retardation film. The linearly polarized light is refracted in two directions due to a difference of velocity.
A first linearly polarized light that is referred to as ‘ordinary light’ is refracted according to Snell's law. However, a second polarized light that is referred to as ‘extraordinary light’ is refracted against the Snell's law. The retardation film applies different phases to the ordinary light and the extraordinary light.
Particularly, the retardation film of which optic axis is tilted with respect to a surface or normal line of the retardation film, compensates light that passes through the liquid crystal display apparatus. Thus, the retardation film increases viewing angle of the liquid crystal display apparatus.
FIG. 1 is a schematic view showing a general liquid crystal display apparatus.
Referring to FIG. 1, a general liquid crystal display apparatus includes an array substrate 10, a color filter substrate 20, a liquid crystal layer 30, a first retardation film 42, a first polarizing plate (or polarizer) 44, a second retardation film 46 and a second polarizing plate (or analyzer) 48. The array substrate 10 includes a first transparent substrate 12, a pixel electrode 14 and a first alignment film 16. The pixel electrode 14 is formed on the first transparent substrate 12. The first alignment film 16 is formed on the pixel electrode 14.
The color filter substrate 20 includes a second transparent substrate 22, a color filter layer 24, protection layer 26, a common electrode layer 28 and a second alignment film 29. The color filter layer 24 is formed on the second transparent substrate 22. The protection layer 26 is formed on the color filter layer 24. The common electrode layer 28 is formed on the protection layer 26. The second alignment film 29 is formed on the common electrode layer 28. The liquid crystal layer is interposed between the array substrate 10 and the color filter substrate 20. The first retardation film 42 is disposed on a backside of the first transparent substrate 12. The first polarizing plate 44 is disposed on the first retardation film 42. The second retardation film 46 is disposed on a backside of the second transparent substrate 46. The second polarizing plate 48 is disposed on the second retardation film 46.
When electric fields are formed between the pixel electrode 14 and the common electrode layer 28, liquid crystal molecules of the liquid crystal layer 30 are erected (Homogeneous phase) or laid (Homeotropic phase) with respect to the array substrate 10 and the color filter substrate 20.
FIG. 2A is a plan view showing vertical angles formed between a first polarizing axis of a first polarizing plate and a second polarizing axis of a second polarizing plate, and FIG. 2B is a perspective view showing vertical angles formed between a first polarizing axis of a first polarizing plate and a second polarizing axis of a second polarizing plate.
Referring to FIG. 2A, when the liquid crystal molecules are erected (or vertically aligned), a light is not leaked in a normal direction of the liquid crystal display apparatus because a polarizing axis of the first and second polarizing plates are substantially orthogonal to each other.
Referring to FIG. 2B, the light is leaked in a tilted direction because the polarizing axis of the first and second polarizing plate are not orthogonal to each other. Thus, a contrast ratio decreases, so that a display quality is deteriorated.
In order to reduce the leakage of the light, a retardation film such as a biaxial film and uni-axial film is disposed at backsides of the first and second transparent substrates 12 and 22 together with the first and second polarizing plates 44 and 48.
The retardation film increases a cost of manufacturing the liquid crystal display apparatus.